asynchronous

protected boolean asynchronous()

If true, this action should be performed asynchronously in a private thread.
If false, it will be performed synchronously as called in the event thread.

The default value is true for compatibility reasons; subclasses are strongly
encouraged to override it to be false, and to either do their work promptly
in the event thread and return, or to somehow do work asynchronously (for example
using RequestProcessor.getDefault()).

You may currently set the global default to false
by setting the system property
org.openide.util.actions.CallableSystemAction.synchronousByDefault
to true.

When true, the current implementation also provides for a wait cursor during
the execution of the action. Subclasses which override to return false should
consider directly providing a wait or busy cursor if the nature of the action
merits it.